It is a requirement of strategic guidance systems that the accelerometers continue to deliver accurate velocity information in the face of expected Power Failure Interruptions (PFI). The PFI requires that sensitive electronic circuits be deactivated and protected in order to prevent damage during the PFI event. This interrupts normal operation of the accelerometers and prevents accumulating and reporting to the guidance system velocity gained during the PFI. To eliminate unacceptable velocity errors, the unreported velocity must be reconstructed from a combination of information saved in hard memory at the onset of the PFI event, and data available in the accelerometer system after the PFI event is over and normal operation re-established. The following describes accelerometer operation during and after the PFI event, and the invention concerns how the unreported velocity information is reconstructed and report to the guidance system at the next interrogation period.